摩訶止觀 9.24

9.24

若依《成論》，無未來禪，故云：「汝說未來禪，將非我欲界定？」《毘曇》則有。尊者瞿沙、《釋論》具出之。佛備兩說，而論主偏申耳。今則逐人判之，自有得欲界定，累月住未到，不久即入初禪。此但稱「欲界」，不言「未到」。有人住欲界不久，在未到經旬，故言「未到」，不云「欲界」；有人具久在二法，故言兩定，不可偏判。今依《大論》備出之。若節節邪、正相，如《修證》中委說。但初禪去欲界近，如疆界多難，應須略知。

If one follows the Tattvasiddhi-śāstra, there is no future [access] dhyāna, which is why it says: 'When you speak of future dhyāna, is that not simply my desire-realm concentration?' In the Abhidharma, however, it exists. The Venerable Ghoṣaka and the Mahāprajñāpāramitopadeśa present it fully. The Buddha provided both explanations, and the treatise masters each expounded one side. Now, we judge according to the individual: some attain desire-realm concentration and dwell in the not-yet-arrived for months, entering the first dhyāna before long. This is merely called 'desire realm' and not spoken of as 'not-yet-arrived.' Others dwell in the desire realm briefly and remain in the not-yet-arrived for ten-day periods; hence it is called 'not-yet-arrived' and not spoken of as 'desire realm.' Others fully dwell in both dharmas for a long time; hence both concentrations are spoken of, and one must not judge one-sidedly. Now, relying on the Da zhidu lun, we present both fully. As for the marks of the incorrect and the correct at each step, they are explained in detail in the Xiuzheng. However, the first dhyāna is close to the desire realm, like a border region with many perils; one must have a brief knowledge of it.